Preparation and Mechanical Properties of Polypropylene−Clay Hybrids

TLDR

The study investigates how different clays and oligomers affect the dynamic moduli of polypropylene–clay hybrids. PP–clay hybrids were produced by melt‑mixing PP, maleic anhydride‑modified polypropylene oligomers, and stearylammonium‑intercalated clays, and the dispersion of the 10‑Å silicate layers was examined by TEM and X‑ray diffraction. Exfoliated, homogeneous hybrids were obtained when the oligomer both intercalated the clay layers and was miscible with PP, leading to storage moduli up to twice that of neat PP between Tg and 90 °C, with the mica‑based hybrid reaching 2.0× PP and 2.4× the PP/PP‑MA blend at 80 °C.

Abstract

Polypropylene (PP)−clay hybrids (PPCH) have been prepared by simple melt-mixing of three components, i.e., PP, maleic anhydride modified polypropylene oligomers (PP-MA), and clays intercalated with stearylammonium. The dispersibility of 10-Å-thick silicate layers of the clays in the hybrids was investigated by using a transmission electron microscope and X-ray diffractometer. It is found that there are two important factors to achieve the exfoliated and homogeneous dispersion of the layers in the hybrids: (1) the intercalation capability of the oligomers in the layers and (2) the miscibility of the oligomers with PP. Almost complete hybrids were obtained in the case where the PP-MA has both intercalation capability and miscibility. The hybrids exhibit higher storage moduli compared to those of PP especially in the temperature range from Tg to 90 °C. The highest relative storage modulus at 80 °C of the hybrid based on a mica and the miscible PP-MA is as high as 2.0 to that of PP and is 2.4 to that of the PP/PP-MA mixture, which is considered to be the matrix of the PPCH. Also, the effects of the kinds of clays and oligomers on the dynamic moduli are discussed.